Field
The present disclosure relates to a hybrid thin film transistor in which different types of thin film transistors are disposed on the same flexible substrate and an organic light emitting display device using the same.
Description of the Related Art
The demand for display devices is increasing. As such, thin, light, and high resolution flat panel display devices (FPD) have replaced bulky cathode ray tube (CRT) displays.
The flat panel display device can be a light crystal display device (LCD), an organic light emitting display device (OLED), or an electrophoretic display device (ED).
The liquid crystal display device, the organic light emitting display device, and the electrophoretic display device which are actively driven each include a thin film transistor substrate in which thin film transistors allocated in a pixel area disposed in a matrix manner are disposed.
The liquid crystal display device (LCD) displays an image by adjusting light transmittance of liquid crystal using an electric field applied thereto. The organic light emitting display device displays an image via organic light emitting diodes in pixels arranged in a matrix manner.
The organic light emitting diode is a self-light emitting element which emits light by itself and is advantageous in terms of a high response speed, high luminous efficiency, high luminance, and a wide viewing angle.
Specifically, the organic light emitting display device (OLED) which uses a characteristic of an organic light emitting diode with excellent energy efficiency is broadly classified into a passive matrix type organic light emitting display (PMOLED) and an active matrix type organic light emitting display device (AMOLED).
In the organic light emitting display device, pixels including organic light emitting diodes and pixel circuits are disposed in a matrix form and luminance of an image is adjusted by pixels which are driven in accordance with a gray scale of video data.
Further, the organic light emitting display device includes a plurality of gate electrode lines, a plurality of data lines, a plurality of power lines, and a plurality of pixels which is connected to the above-mentioned lines to be disposed in a matrix form. Each pixel includes an organic light emitting diode configured by an organic light emitting layer between an anode and a cathode and a pixel circuit which independently drives the organic light emitting diode. The pixel circuit is mainly configured by a switching transistor which transmits a data signal, a driving transistor which drives the organic light emitting diode in accordance with the data signal, and one capacitor which maintains a data voltage. The switching transistor charges the data voltage into the capacitor in response to a scan pulse. The driving transistor adjusts a light emission amount of the organic light emitting diode by controlling a current amount supplied to the organic light emitting diode in accordance with the data voltage charged in the capacitor. Further, a turn-on time of the switching transistor may be shorter than that of the driving transistor. The turn-on time of the transistor is related to power consumption of the organic light emitting display device.
In accordance with the active development of personal electronic devices, display devices have been also developed as products which are superior in portability and wearability. As described above, in order to apply the display device to the portable or wearable device, a display device with low power consumption is required. However, technologies related to the display devices developed so far have limitations in realizing low power consumption.
Therefore, in recent years, in order to overcome the above-described problems, there is a necessity for a new pixel structure and a new organic light emitting display device which can drive the pixels with low power consumption.